Ok so the bike was running fine last season, left it neglected over the winter. It will not start now. There is a weak spark at the plug, fuel seems fine, carbs all good with fresh fuel. It has new coils, leads NGK caps, points, condensers and plugs. I am stumped! Probably missing something obvious but just cant see it at the moment. The coils are aftermarket, however it makes not difference when I try an original set. Any advice will be gratefully received.